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Luke Cole, an early leader of the environmental justice movement, which holds that many minority neighborhoods have become toxic dumping grounds because their residents are poor and powerless, died Saturday in Uganda. He was 46 and lived in San Francisco.

Mr. Cole was killed in a head-on traffic accident when a truck veered across the road, his father, Herbert Cole, said. His wife, Nancy Shelby, was seriously injured. The couple was on vacation.

As executive director of the Center on Race, Poverty and the Environment, an organization based in San Francisco that he founded in 1989 with Ralph Abascal, Mr. Cole played a key role in several significant environmental law cases.

In the mid-1990s, he represented residents of Kettleman City, Calif., most of them Hispanic, in their campaign to stop Chemical Waste Management Inc. from building a toxic-waste incinerator there. Kettleman City, in the San Joaquin Valley, was already the site of a vast toxic-waste landfill. A state court enjoined the company from constructing the incinerator.

Even more, the court invalidated the environmental-impact report issued by Kings County, Calif., citing its failure to translate even the summary of the study into Spanish.

“It really raised the issue of systemic exclusion of communities from understanding environmental decisions that affect their lives,” Bradley Angel, executive director of Greenaction for Health and Environmental Justice, said in an interview.

“Luke actually began this work before the term ‘environmental justice’ was in widespread use,” Mr. Angel said.

More recently, Mr. Cole represented a group of residents of the Waterfront South neighborhood in Camden, N.J. — most of them black or Hispanic — who took the unusual action of citing the Civil Rights Act of 1964 in a lawsuit against the New Jersey Department of Environmental Protection.

The plaintiffs claimed that the department had violated their rights by issuing a permit to build a concrete grinding plant without considering that it had already granted more than twice as many industrial permits for Waterfront South as were found in the typical New Jersey ZIP code.

They also argued that more than 20 percent of Camden’s contaminated sites — abandoned factories, a chemical plant, waste-treatment plants, automotive shops and a petroleum coke transfer station — were in their neighborhood. In 2001, the United States District Court in Camden ruled in favor of the plaintiffs.

“It marked the first recognition by any court that African-Americans and Latinos were experiencing discrimination with regard to the siting of noxious, polluting facilities,” said Olga Pomar, a lawyer with South Jersey Legal Services and a co-counsel in the case. “That sparked greater awareness among environmental justice activists.”

Later that year, however, the United States Court of Appeals for the Third Circuit declared in a related case that private citizens did not have a legal right to enforce the antidiscrimination regulations that were the basis of their claim. Only the federal Environmental Protection Agency had that right, the appeals court said. In effect, the ruling overturned the decision in the Camden case.

From 1996 through 2000, Mr. Cole served on the E.P.A.’s national environmental justice advisory council.

Luke Winthrop Cole was born in North Adams, Mass., on July 15, 1962, one of three children of Herbert Cole, a professor of art history, and Alexandra Chappell Cole, an architectural preservationist. Besides his parents and his wife, Mr. Cole is survived by a son, Zane; his stepmother, Shelley Reed Cole; two brothers, Peter and Thomas; his sister, Sarah Cole; and a stepbrother, Daryn Kenny.

Mr. Cole graduated from Stanford in 1984 and then worked for three years in Washington as one of Ralph Nader’s so-called Nader’s Raiders, editing a consumer advice newsletter. After receiving his law degree from Harvard in 1989, he moved to San Francisco and soon after started the Center on Race, Poverty and the Environment.

The environmental rights of American Indians were of particular interest to Mr. Cole. In one California case, he represented the Timbisha Shoshone tribe, which is trying to halt open-pit gold mining using cyanide to leach out the gold on ancestral land in Death Valley. A ruling in pending.

In another case, he helped residents of Kivalina, an Inuit village in northwest Alaska, sue the Teck Corporation, claiming that the company’s zinc and lead mine had polluted the village water supply for years.

A settlement, reached last year, called for Teck to stop depositing mining tailings into the Kivalina River and to build a pipeline to the ocean, about 50 miles away.

But legal action is not the ultimate solution to environmental discrimination, Mr. Cole told The New York Times in 1993.

“The only way to ever decisively and permanently win these battles is through the political process,” he said. “When a community organizes itself at the grass roots, we can exercise our power, the power of people.”